X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;f=src%2Fopenssl%2Fcipher.c;h=974fbeb2e9966e1d189fa6c7737aa63aa1e1a025;hb=2b0aeec02d64bb4724da9ff1dbc19b7d35d7c904;hp=17ad408b317dd7465eb576c06c28040aa7708f33;hpb=edc1efed3c0cf5aebb1c765066c0413757229a31;p=tinc

diff --git a/src/openssl/cipher.c b/src/openssl/cipher.c
index 17ad408b..974fbeb2 100644
--- a/src/openssl/cipher.c
+++ b/src/openssl/cipher.c
@@ -1,6 +1,6 @@
 /*
     cipher.c -- Symmetric block cipher handling
-    Copyright (C) 2007-2016 Guus Sliepen <guus@tinc-vpn.org>
+    Copyright (C) 2007-2017 Guus Sliepen <guus@tinc-vpn.org>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -33,17 +33,20 @@ struct cipher {
 };
 
 static cipher_t *cipher_open(const EVP_CIPHER *evp_cipher) {
-	cipher_t *cipher = xzalloc(sizeof *cipher);
+	cipher_t *cipher = xzalloc(sizeof(*cipher));
 	cipher->cipher = evp_cipher;
 	cipher->ctx = EVP_CIPHER_CTX_new();
-	if(!cipher->ctx)
+
+	if(!cipher->ctx) {
 		abort();
+	}
 
 	return cipher;
 }
 
 cipher_t *cipher_open_by_name(const char *name) {
 	const EVP_CIPHER *evp_cipher = EVP_get_cipherbyname(name);
+
 	if(!evp_cipher) {
 		logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher name '%s'!", name);
 		return NULL;
@@ -54,6 +57,7 @@ cipher_t *cipher_open_by_name(const char *name) {
 
 cipher_t *cipher_open_by_nid(int nid) {
 	const EVP_CIPHER *evp_cipher = EVP_get_cipherbynid(nid);
+
 	if(!evp_cipher) {
 		logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher nid %d!", nid);
 		return NULL;
@@ -63,23 +67,45 @@ cipher_t *cipher_open_by_nid(int nid) {
 }
 
 void cipher_close(cipher_t *cipher) {
-	if(!cipher)
+	if(!cipher) {
 		return;
+	}
 
 	EVP_CIPHER_CTX_free(cipher->ctx);
 	free(cipher);
 }
 
 size_t cipher_keylength(const cipher_t *cipher) {
-	if(!cipher || !cipher->cipher)
+	if(!cipher || !cipher->cipher) {
 		return 0;
+	}
 
 	return EVP_CIPHER_key_length(cipher->cipher) + EVP_CIPHER_iv_length(cipher->cipher);
 }
 
+uint64_t cipher_budget(const cipher_t *cipher) {
+	/* Hopefully some failsafe way to calculate the maximum amount of bytes to
+	   send/receive with a given cipher before we might run into birthday paradox
+	   attacks. Because we might use different modes, the block size of the mode
+	   might be 1 byte. In that case, use the IV length. Ensure the whole thing
+	   is limited to what can be represented with a 64 bits integer.
+	 */
+
+	if(!cipher || !cipher->cipher) {
+		return UINT64_MAX;        // NULL cipher
+	}
+
+	int ivlen = EVP_CIPHER_iv_length(cipher->cipher);
+	int blklen = EVP_CIPHER_block_size(cipher->cipher);
+	int len = blklen > 1 ? blklen : ivlen > 1 ? ivlen : 8;
+	int bits = len * 4 - 1;
+	return bits < 64 ? UINT64_C(1) << bits : UINT64_MAX;
+}
+
 size_t cipher_blocksize(const cipher_t *cipher) {
-	if(!cipher || !cipher->cipher)
+	if(!cipher || !cipher->cipher) {
 		return 1;
+	}
 
 	return EVP_CIPHER_block_size(cipher->cipher);
 }
@@ -87,13 +113,15 @@ size_t cipher_blocksize(const cipher_t *cipher) {
 bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
 	bool result;
 
-	if(encrypt)
+	if(encrypt) {
 		result = EVP_EncryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher));
-	else
+	} else {
 		result = EVP_DecryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + EVP_CIPHER_key_length(cipher->cipher));
+	}
 
-	if(result)
+	if(result) {
 		return true;
+	}
 
 	logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 	return false;
@@ -102,13 +130,15 @@ bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
 bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
 	bool result;
 
-	if(encrypt)
+	if(encrypt) {
 		result = EVP_EncryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - EVP_CIPHER_key_length(cipher->cipher), (unsigned char *)key + len - EVP_CIPHER_iv_length(cipher->cipher) - EVP_CIPHER_key_length(cipher->cipher));
-	else
+	} else {
 		result = EVP_DecryptInit_ex(cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - EVP_CIPHER_key_length(cipher->cipher), (unsigned char *)key + len - EVP_CIPHER_iv_length(cipher->cipher) - EVP_CIPHER_key_length(cipher->cipher));
+	}
 
-	if(result)
+	if(result) {
 		return true;
+	}
 
 	logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 	return false;
@@ -117,16 +147,24 @@ bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encry
 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 	if(oneshot) {
 		int len, pad;
+
 		if(EVP_EncryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
-				&& EVP_EncryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
-				&& EVP_EncryptFinal(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
-			if(outlen) *outlen = len + pad;
+		                && EVP_EncryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
+		                && EVP_EncryptFinal_ex(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
+			if(outlen) {
+				*outlen = len + pad;
+			}
+
 			return true;
 		}
 	} else {
 		int len;
+
 		if(EVP_EncryptUpdate(cipher->ctx, outdata, &len, indata, inlen)) {
-			if(outlen) *outlen = len;
+			if(outlen) {
+				*outlen = len;
+			}
+
 			return true;
 		}
 	}
@@ -138,16 +176,24 @@ bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *ou
 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 	if(oneshot) {
 		int len, pad;
+
 		if(EVP_DecryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
-				&& EVP_DecryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
-				&& EVP_DecryptFinal(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
-			if(outlen) *outlen = len + pad;
+		                && EVP_DecryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
+		                && EVP_DecryptFinal_ex(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
+			if(outlen) {
+				*outlen = len + pad;
+			}
+
 			return true;
 		}
 	} else {
 		int len;
-		if(EVP_EncryptUpdate(cipher->ctx, outdata, &len, indata, inlen)) {
-			if(outlen) *outlen = len;
+
+		if(EVP_DecryptUpdate(cipher->ctx, outdata, &len, indata, inlen)) {
+			if(outlen) {
+				*outlen = len;
+			}
+
 			return true;
 		}
 	}
@@ -157,8 +203,9 @@ bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *ou
 }
 
 int cipher_get_nid(const cipher_t *cipher) {
-	if(!cipher || !cipher->cipher)
+	if(!cipher || !cipher->cipher) {
 		return 0;
+	}
 
 	return EVP_CIPHER_nid(cipher->cipher);
 }